In this work we present an ongoing analysis of data collected by the UVIS and LNO channels of the Nadir and Occultation for MArs Discovery spectrometer (NOMAD, [1]), onboard the ExoMars Trace Gas Orbiter (TGO) spacecraft currently orbiting Mars. We will show how the two channels can be combined to obtain information about Martian dust densities and grains sizes. The retrieval of these properties is performed by means of the MITRA radiative transfer tool [2,3,4]. The method is validated on a NOMAD orbit registered during the 2018 global dust storm and its most critical issues are discussed.